P1.2.1 - Changes of state

• Q1. What is density?

  Density tells you how much mass there is in a certain volume
• Q2.

  If you have two different sized blocks made of the same material the density of the blocks is the same
• Q3.

  Density is a property of a material , not of an object.
• Q4. What does the mass of each block depend on?

  Its volume
• Q5. How do u calculate density?

  Density = Mass(kg) divided by volume (m³)
• Q6.

  The density of a block depends on its mass and volume
• Q7. A classroom has a volume of 300m³. the mass of air in the room in is 3.6 kg. Calculate the density of the air.

  Answer = 0.012kg/m³

  Step 1: Write down what you know.

  mass = 3.6kg

  volume = 300m³

  step 2: calculate the answer and give correct units

  density = mass ÷ volume

  3.6kg ÷ 300m³ = 0.012kg/m³
• Q8. Why is a substance denser as a solid than as a liquid or gas?

  In solid states the mass of 1cm is greater than 1cm of a gas , meaning the solids density is also greater
• Q9.

  Density does not depend only on the particle arrangement, but also on the mass of the particles
• Q10. What is the Law of Conservation ( Conservation of mass)

  Particles do not appear or disappear
• Q11. When can this apply?

  It applies when substances change state by melting , freezing , evaporating or condensing. If 1g of ice melts you then have 1g of water. Water molecules don't disappear